1. Field of the Invention
The present invention relates to a power supply circuit for supplying electric power to an exposure display device, an exposure control device etc. incorporated in a photographic camera.
2. Description of the Prior Art
The power supply switch for making and interrupting connection between a power source and electric circuits, if rendered continuously conductive for example by defective insulation, gives rise to an unnecessary power supply to the loads, thus leading to an accelerated consumption of power battery.
In recent photographic cameras there is proposed the use, on the upper end of the shutter button, of a so-called touch-switch the electrodes of which are composed of the central portion and the peripheral portion of the shutter button, said switch being designed to function based on a weak current formed when said electrodes are bridged with a finger to reduce the resistance therebetween. Said electrodes are mutually separated in ordinary state by an insulating material, but the above-mentioned drawback may appear in case of defective insulation caused when the surface of said insulating material is smeared. The power supply circuit of the present invention is particularly useful in case the switch of the above-mentioned structure is used as the power switch.